in a Ki84
if I am fast (did I just get to 15K or have I been cruising along)
I would head directly to them...depending on my speed, I would try to go for some ALT on them....
you have a much better chance of killing them all if they are trying to come up to you....
fake attacks....try to get them all in the same air space....much easier to reverse 4 cons all close to each other then spread out all over....
fight in the vert, yes even against K4....
time your merge to when they are stalled out, land your hits at convergence....
if they are much faster I would slow down even more and just use over shoots and land hits as they pass by.....fighting nose down, but de-throttled....if they all slow down to within flaps usage, convert immediately to the vert fight....
the best fighters can switch it up with out thinking about it.